The present invention relates in general to a casting apparatus for electrophoretic gel trays, and more particularly, to such an apparatus adapted for casting a separation medium such as agarose and polyacrylamide gels in an open ended gel tray for horizontal gel electrophoresis, for example, in DNA separation systems.
Electrophoresis is an analytical method widely used in research and increasingly advantageous for clinical and analytical processes. While there is known a variety of electrophoresis devices and methods, e.g., thin-film and column electrophroesis, the type of electrophoresis with which the present invention is principally concerned is commonly referred to as horizontal gel electrophoresis. In this regard, for many educational, laboratory, medical, research or industrial purposes, gel electrophoresis has been employed to study migration of a substance in a suitable retarding medium and/or to effect separation of complex substances by differential migration in such media. The driving force for inducing the migration is an applied electric field, where the medium is capable of retarding the movement of the substance as a function of its molecular weight, charge and molecular size.
Electrophoresis is carried out in the separation medium which is cast to a predetermined thickness in a gel tray typically having open ends. In order to permit the formation of a gel layer of predetermined thickness, the gel tray is placed into a casting apparatus enclosed on all four sides, so as to overcome the necessity of having to tape up the open ends of the tray in order to pour the gel. As gel trays are used in a variety of sizes, there is the need to inventory a corresponding number of casting apparatus of compatible sizes. In addition, as each casting apparatus can accommodate only one gel tray at a time, multiple trays of the same size cannot be prepared simultaneously with a gel layer for increased efficiency of operation. As both the casting apparatus and gel trays are relatively expensive, the necessity of maintaining a large number of same is undesirable.
The foregoing casting apparatus, although enclosing the gel tray on all four sides, often provides an ineffective seal at the open ends of the tray. As a consequence, hot gel when poured into the gel tray, can leak around the open ends of the tray and under its peripheral edges. Once the hot gel solidifies, it becomes relatively difficult to remove the gel tray from the casting apparatus, as the solidified gel acts as an adhesive. The force necessary to remove the gel tray can result in breakage to the tray or injury to the formed gel layer. Accordingly, it can be appreciated that there is an unsolved need for a casting apparatus which is adapted to accommodate multiple gel trays of the same or different size and one which provides a positive seal at the open ends of the tray while facilitating its removal upon solidification of the gel.